The present invention relates to end cap insulation for an electromagnetic device and more particularly to an improved end wire insulation assembly for a stator core having pole pieces circumferentially spaced about the central axis of the core.
In the construction of stators for electromagnetic motors, laminations of ferromagnetic material are stacked together to form a stator core with pole pieces circumferentially spaced about the central axis of the core separated by openings extending through the core. Magnet wires are wound by automated winding around each pole to extend through adjacent openings on opposite side flanks of the same pole with the end turns of the winding passing over end cap insulation structure mounted on opposite core faces as described hereinafter. The laminations forming each pole further provide a slot in each pole through which a shading element, advantageously formed of copper extends to protrude slightly outward from each of the stator core end faces. An endless isulating sleeve, advantageously of a flexible pliable plastic material (often a thermoplastic polyester material) is formed into an endless shape to conform with and cover the side walls of the openings through which the automated wound magnet wires extend.
As is disclosed in U.S. Pat. No. 4,340,829, issued to Billy R. McCoy on July 20, 1982, it is known in the art to provide molded end cap structure of insulating material designed for attachment to each end face of the ferromagnetic stator core before magnet wires are wound through adjacent openings on the side flanks of each pole and through corresponding openings in the end cap structure with the end turns of the wound magnet wires passing over end cap structure surrounding such corresponding openings. As is also disclosed in this aforementioned patent, it is generally known to provide retaining means in the end cap structure to overlie the edges of the endless insulating sleeve to retain the sleeve against accidental axial dislodgement from the opening in which it is has been inserted. Further, it is generally known, as also is disclosed in the aforenoted patent, to provide recesses in the undersurface of each molded insulator, disposed to receive the protruding tips or extremities of shading elements which extend outwardly of each end face of a stator core, two spaced recesses being associated in each molded insulator cap for each shading element so that the same insulator cap can engage either end face of the core without interference from the opposed protruding tips or extremities of the shading pieces.
In accordance with the present invention, it has been recognized that the stator core opening insulating sleeve does not always conform to the magnetic coil opening with which it is associated, particularly during automatic winding operations either as a consequence of machining discrepancies between the stator core opening insulating sleeve and the opening with which it is associated or as a consequence of or combined with distorting forces imparted during automated winding operations, particularly during the early stages of the automated winding operations. Further, the present invention has recognized that the mere provision of recesses in the undersurface of molded end cap structure to accommodate the protruding tips or extremities of shading elements has often failed to insure insulation of these protruding extremities from adjacent magnetic coil windings. Recognizing these deficiencies in past molded end cap insulating assembly structures, the present invention provides a straight-forward, efficient and economical to manufacture and assemble molded end cap structure and a novel resilient insulating liner member for a stator core opening adapted to cooperate with an opening in the stator core and the corresponding opening in such end cap structure, such liner member being by its free-ended configuration and resilient nature capable of resiliently conforming with the opening notwithstanding possible manufacturing discrepancies between the stator core opening and the insulating sleeve. Furthermore, such resiliently conforming liner is restrained by said molded end cap structure from not only axial but also radial movement within the core opening with which it resiliently conforms. In addition, the present invention provides a uniquely shaped recess in the undersurface of molded end cap structure to accommodate a protruding extremity of a shading element and insure the insulation of the same from an adjacent magnet coil winding.
Various other features of the several parts of the inventive opening insulating liner, stator end cap insulator, and shading element extremity recess therein will become obvious to one skilled in the art upon reading the disclosure set forth herein.